This invention relates to carbon composites and more particularly to methods of bonding carbon composite pieces.
There is an acute need for new methods of joining carbon/carbon, and graphite/aluminum (Gr/Al) composites. The methods used today are bonding with epoxies, diffusion bonding, ceramic adhesives, and fusion welding. In each method the joints are poor in that there is porosity, degradation of the carbon or graphite fiber, reaction with the matrix, and heat affected zones (HAZ) not conducive to good performance. For example, epoxies used to bind carbon/carbon break down at about 500.degree. C., well below the temperature limit for carbon and graphite. Another example is the use of diffusion bonding to join Gr/Mg and Gr/Al metal matrix composites (MMC's). At present, diffusion bonding is the only conventional process capable of joining those MMC's together. However, diffusion bonding, which requires long times at high temperatures under high pressures in an inert environment, is not ideal because of the tendency of graphite to react with the magnesium or aluminum matrix under long exposures. Moreover, if a tubular joint is to be made, the difficulty of diffusion bonding is much greater than flats due to the need to devise special dies needed to adequately apply the pressure on a tube curvature.
Finally, it would be useful to provide a method of producing good bonds between carbon/carbon composites and graphite/aluminum composites.